Forensic Aspects of Designer LSD Analogs Identification by GC–MS (EI) and UV Spectroscopy

Lysergic acid diethylamide (LSD) analogs, often referred to as new psychoactive substances, are synthesized to mimic controlled substances while evading drug regulations. This study emphasizes the challenges of identifying these compounds, particularly their isomeric forms. Gas chromatography-mass spectrometry (GC-MS) and UV spectroscopy were employed to analyze 13 LSD analogs. The effects of different solvents on the detection of these analogs were analyzed, demonstrating that solvents like diethyl ether, <i>tert</i>-butyl methyl ether, dichloromethane and acetone provided the best sensitivity and stability. Methanol, on the other hand, causes alcoholysis of many LSD analogs, which may lead to false results. Additionally, effective chromatographic separation of isomers was established, including LSD, MiPLA, LAMPA, 1P-LSD and 1P-MiPLA, as well as 1cP-LSD and 1cP-MiPLA, which is crucial for accurate identification. The elution order of the determined compounds with the use of developed chromatographic method was as follows: LSD, MiPLA, LAMPA, AL-LAD, LSZ, 2-Br-LSD, ALD-52, 1P-LSD, 1P-MiPLA, 1B-LSD, 1V-LSD, 1cP-LSD and 1cP-MiPLA. Differences in ion ratios observed in mass spectrometry (MS) were also analyzed to distinguish between closely related compounds. Several key ions for LSD analogs were able to be identified, including 221, 208, 207, 196, 194, 192, 181, 167, 154, 152 and 128 <i>m</i>/<i>z</i>. In analogs with an <i>N</i>-diethyl group (or variants like <i>N</i>-methyl-propyl in LAMPA or <i>N</i>-methyl-isopropyl in MiPLA), mass spectra showed fragments 100, 72 and 58 <i>m</i>/<i>z</i>. For LSZ, the cyclic group at R1 produces ions 98 and 70 <i>m</i>/<i>z</i>. Analogs with an <i>N</i>6 allyl group (e.g., AL-LAD) show a characteristic ion 247 <i>m</i>/<i>z</i>. This method allows for the correct differentiation of structural isomers based on their unique ion fragmentation patterns and relative intensities. UV spectroscopy was used as a supplementary tool for screening, though it has limitations in analyzing complex mixtures. This work contributes to the forensic identification of designer LSD analogs, ensuring reliable detection for legal and toxicological investigations.